1. Field
On or more embodiments relate to a piezoelectric micro speaker, and more particularly, to a piezoelectric micro speaker which may be mounted on a surface of an electronic device.
2. Description of the Related Art
Due to rapid development of terminals for personal voice communications and data communications, amounts of data to be transmitted and received has increased, while the terminals are required to be small and multifunctional.
In response to these trends, research into acoustic devices using micro-electro-mechanical system (MEMS) technology has been conducted. In particular, MEMS technology and semiconductor technology make it possible to manufacture micro speakers with small size and low costs according to a package process and to easily integrate micro speakers with peripheral circuits.
Speakers using MEMS technology can be classified into electrostatic type micro speakers, electromagnetic type micro speakers, and piezoelectric type micro speakers. Piezoelectric type micro speakers can be driven at lower voltages than electrostatic type micro speakers, and have simpler and slimmer structures than the electromagnetic type micro speakers.
A piezoelectric micro speaker includes a piezoelectric actuator placed on a surface of a diaphragm. The piezoelectric actuator includes two electrode layers and a piezoelectric layer therebetween. When the piezoelectric micro speaker is mounted on a surface of an electronic device, the acoustic characteristics of the micro speaker may change due to a too short or not constant distance between a vent hole formed in a rear surface of the piezoelectric micro speaker and a surface of a printed circuit board (PCB) where the micro speaker is mounted.